Rusting satellite dish

The dish needs to be smooth or there will be some loss. If already rusted, you should get a new dish. That is assuming you are using one of the small units for Direct tv or Dish. The very high wavelength needs a smoother surface than the older 10 foot size dishes.

The paint should be of the type that does not have conductive particals in it.

Most of the 0.6m DBS reception problems I've seen are the result of bad or unstable dish aiming. However, if you experience fades and dropouts, the easiest fix is to just buy a bigger dish. Mine is 1.0m diameter:

Yes. Ferrite (iron oxide) is an RF absorber. If you want to turn your dish into a radar invisible stealth aircraft simulation, just let it rust a little. To be fair, the layer of rust has to be fairly thick in order to have an effect, so you might be able to get away with it.

Paint that contains no carbon, graphite, iron oxide, or any other additive that might be considered an RF absorber.

Or, you could just let your imagination run wild:

I'm all for repairing things, even if they're not worthy of the effort. I would use automotive body putty to fill the hole, and a piece of aluminum foil to replace the missing part of the reflector. Getting the foil to simulate a parabolic shape will be difficult, but not impossible. I suggest a wooden form.

Also, note that the color and surface finish of the dish is rather important. The common gray color is designed to both reflect and absorb a minimum amount of heat from the sun. If the dish were a mirror finish, when the sun goes behind the satellite belt twice each year, the reflected light would burn up the LNB. I've had it happen on larger dishes. If the dish were painted flat black, it would absorb enough heat to distort and temporarily loose shape. I don't know how Dish Networks gets away with black reflectors. The surface finish is a compromise between smooth for maximum gain, and matt for minimum light reflection. Whatever you do, don't paint it with glossy paint or you will cook the LNB.

Is it a solid dish or a mesh one? I don't think I'd be bothered to

From the email address, I'd say it's more likely for Astra 28.2E satellites.

Hmm. OT maybe, but........ a little bit ago we needed to measure a large n umber of throws of Frisbee golf discs. I had one of those big reflective r ound traffic signs, about the size of a good size satellite disc. It was a No Entry One Way (but the international symbol, not words). That thing re ally reflects, my little LED headlamp will light it up two blocks away. Th e back of it is just gray sheet metal but the front, wow, that reflective p aint is great stuff.

So the plan was have the kids throw from where the sign was set up, then go to where each disc lands and shoot back to the sign with my laser range fi nder.

Surprise. The range finder won't read off a reflective sign at all, at any distance. Turned the sign around and it read fine off the unpainted back. I hadn't expected that.

Oh, there's a solution for that, from the world of architecture. Plant ivy. Seriously, there's very little effect unless the dish changes shape; the Arecibo telescope doesn't look like a shiny-new dish, and it focuses radio just fine. And a thin layer of paint won't keep the underlying metal from blocking the passage of radio waves, so it'll still reflect if you decide to apply some finish.

That's a surprise to me too. I thought the laser range-finding to the Moon was done using a retro-reflector placed there specially by visitors. But maybe they did not use a road-sign...

Mike.